Trying to produce a Random list of single digit integers which are not repeated. Getting only 5 instead of 9

Question

Here is my code

from random import randint
SudList = []
numbers = [1,2,3,4,5,6,7,8,9]
for i in numbers:
    SudList.append(numbers[randint(0,len(numbers)-1)])
    print("Sudlist-" + str(SudList))
    numbers.remove(SudList[-1])
    print("numbers-" + str(numbers))
print(SudList)

I expected this code to return something like this- (the final SudList)

[9,7,2,8,6,4,5,3,1]

But Instead it Returns something like this -

[9,4,6,7,2]

Here is the whole output-

Sudlist-[5]
numbers-[1, 2, 3, 4, 6, 7, 8, 9]
Sudlist-[5, 1]
numbers-[2, 3, 4, 6, 7, 8, 9]
Sudlist-[5, 1, 9]
numbers-[2, 3, 4, 6, 7, 8]
Sudlist-[5, 1, 9, 3]
numbers-[2, 4, 6, 7, 8]
Sudlist-[5, 1, 9, 3, 4]
numbers-[2, 6, 7, 8]
[5, 1, 9, 3, 4]
Press any key to quit

How do i correct my code?

Well - you are removing elements from the list while iterating over it...? Any reason you can't use `random.shuffle` ? — Jon Clements, Jul 11 '16 at 17:43
Also, take a look at [this](http://stackoverflow.com/q/6500888/198633) — inspectorG4dget, Jul 11 '16 at 17:47

Rahul K P · Answer 1 · 2016-07-11T17:53:24.860

3

You can use shuffle. It's will meet your needs.

import random
random.shuffle(numbers)

output

[7, 4, 3, 2, 1, 8, 6, 5, 9]

edited Jul 11 '16 at 17:53

answered Jul 11 '16 at 17:43

Rahul K P

15,740
4
35
52

this is what i ended up using. Thanks for answering – Anvit Jul 12 '16 at 04:24

score 2 · Accepted Answer · answered Jul 11 '16 at 17:46

2

If you wish to stick with this piece of code, simply use i in range len(numbers) instead of i in numbers. Your remove statement is reducing the length of numbers and thus, the number of numbers printed is always (len(numbers)+1)/2

from random import randint
SudList = []
numbers = [1,2,3,4,5,6,7,8,9]
for i in range(len(numbers)):
    SudList.append(numbers[randint(0,len(numbers)-1)])
    print("Sudlist-" + str(SudList))
    numbers.remove(SudList[-1])
    print("numbers-" + str(numbers))
print(SudList)

answered Jul 11 '16 at 17:46

Vaibhav Bajaj

1,934
16
29

That did it! thanks! Probably gonna use shuffle though – Anvit Jul 12 '16 at 04:22
Yeah, sure! Happy I could help – Vaibhav Bajaj Jul 12 '16 at 04:52

score 2 · Answer 3 · answered Jul 11 '16 at 17:46

2

If you want to stay with your implementation just change:

for i in numbers:

To:

for i in range(len(numbers)):

So you don't iterate over the list that changes

answered Jul 11 '16 at 17:46

Ohad Eytan

8,114
1
22
31

1

Wow, we thought of the same thing at nearly the same time! – Vaibhav Bajaj Jul 11 '16 at 17:47
1

How about `while numbers:` ? :) – PM 2Ring Jul 11 '16 at 17:50

LukeGeneva · Answer 4 · 2016-07-11T19:02:00.263

As has been mentioned, shuffle is the quickest and most readable solution.

import random

numbers = [1,2,3,4,5,6,7,8,9]
random.shuffle(numbers)
print(numbers)

However, it looks like you're wanting to see the state of each list at every step, so if you're looking for a custom implementation, you could also try the following:

from random import randint

Sudlist = []
numbers = [1,2,3,4,5,6,7,8,9]

while len(numbers) > 0:
    index = randint(0, len(numbers) - 1)
    Sudlist.append(numbers.pop(index))
    print('Sudlist-' + str(Sudlist))
    print('numbers-' + str(numbers))
print(Sudlist)

Trying to produce a Random list of single digit integers which are not repeated. Getting only 5 instead of 9

4 Answers4